In which subdirectory of /proc is information about PC Cards, which are connected and recognized
by a 2.6 kernel stored? Please enter the complete path.

Answer: /proc/bus/pccard

Explanation:
See See http://tldp.org/HOWTO/PCMCIA-HOWTO-7.html
On 2.2 and later kernels, the PCMCIA package will create a tree of status information under
/proc/bus/ pccard. Much of the information can only be interpreted using the data sheets for the PCMCIA host controller.
Its contents may depend on how the drivers were configured, but may include all or some of the
following:
/proc/bus/pccard/{irq,ioport,memory} If present, these files contain resource allocation information to supplement the normal kernel resource tables. Recent versions of the PCMCIA system may obtain additional resource information from the Plug and Play BIOS if configured to do so.
/proc/bus/pccard/drivers In recent releases, this lists all currently loaded PCMCIA client drivers.
Unlike /proc/modules, it also lists drivers that may be statically linked into the kernel.
/proc/bus/pccard/*/info For each socket, describes that socket’s host controller and its capabilities.
/proc/bus/pccard/*/exca This contains a dump of a controller’s “ExCA” Intel i82365sl-compatible
register set.
/proc/bus/pccard/*/{pci,cardbus} For CardBus bridges, a dump of the bridge’s PCI configuration
space, and a dump of the bridge’s CardBus configuration registers.